Back in October, the directors of Subaru, Japan’s 8.2-meter telescope at the summit of Mauna Kea in Hawaii, and Gemini, twin 8.1-metre telescopes in Hawaii and Chile, signed an agreement allowing them to apply for time on each other’s telescopes without limits. Nature News reports.

The agreement gives Japanese astronomers access to astrophysical objects in the southern skies above Chile, as well as use of forthcoming instruments for studying extrasolar planets. Gemini users from the U.S., Canada, Brazil, Argentina, Australia, and Chile will get to use Subaru’s new wide-field camera.

With past arrangements, only a handful of nights were exchanged. This speaks to a shift taking place at large ground-based astronomical facilities: collaboration rather than competition.

Previously, many large observatories had developed a full suite of basic instruments to take on their rivals on every astronomical front -- even though those instruments often sat idle because only one could be used at a time.

Having to build an instrument for every occasion wastes a lot of resources, especially when several instruments are just sitting around.

Since Gemini (top) and Subaru (right) are public facilities, negotiating a time-sharing agreement was relatively easy – compared to agreements between public and private ones. As an incentive for the latter, the U.S. government’s Telescope System Instrumentation Program (TSIP) gave money to private observatories to build new instruments – and in return, they’d gave a specified number of nights on those telescopes to US astronomers at large. The program was cancelled in this year but might be resurrected in some form in 2014.

Gemini and Subaru astronomers can start swapping telescope time this coming spring.